Well, I know about the ongoing myth that says the Yamaha NS10 sounds bad and that if your mix sounds good on them, it will sound good on any speakers. This is not true. The Yamaha NS10 sounds VERY GOOD, accurate and not fatiguing. I use them every day. These are my main speakers for years, and they are right in front of me as I type this, playing a Metallica track. There’s all sorts of belief that runs about the Yamaha NS10, and this video here sums them up very well:
I like them so much I have an extra pair I bought directly from Japan as a spare, just in case one breaks.
But anyway, I am sure that to make a good speaker sound good, it takes effort and dedication put into the room acoustics. If people want to believe this or that, it will keep more gems affordable, and I am fine with it.
If a speaker gets popular with casual listeners, it's probably because it delivers a smooth, warm, and rich sound, characteristics that are typically not associated with flat, accurate, or analytical speakers.